Gas-filled tube in which the current is limited



June 13, 1939. H. DIAMOND 2,162,478

GAS-FILLED TUBE IN WHICH THE CURRENT IS LIMITED Filed Aug. 20, 1957 WITNESSES: INVENTOR 5d v @merLD/amand GZMZ flaw, BY

ATTORN EY Patented June 13, 1939 UNITED STATES,

.GAS-FILLED TUBE IN WHICH THE CURRENT .IS LIMITED -Hymen Diamond, Pittsburgh, Pa.,' ass'ignor 'to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa'., a corporation of Pennsylvania Applicatioin August 20, 1937, Serial No. 160,010

5. Claims.

My invention relates to current limiting apparatus, and it has particular relation to current limiting systems in which the current or power supplied to a consumption circuit is maintained below a predetermined value by the operation of an electronic discharge.

It is an object of my invention to provide simple and inexpensive apparatus for limiting the current supplied by a source of electrical energy to a consumption circuit.

Another object of my invention is to provide apparatus of simple structure for protecting the load or network against over-currents such as those arising from short circuits and surges.

Other objects and advantages of the invention will be apparent from the following description and drawing in which the single figure is a view, partly in cross-section and partly in elevation, of a tube and a diagrammatic circuit applied thereto disclosing a preferred embodiment of my invention.

In the drawing I have disclosed the container l preferably of the glass'bulb type enclosing the gaseous atmosphere II which may be of mercury vapor or any one of the other common gases such as neon, etc. The anode l2 therein may be of any suitable construction.

I use an electron emitting cathode l3 and I prefer to enclose this electron emitting cathode in a metal enclosure M. It. preferably has a small opening IS in the top portion facing the anode.

Surrounding the casing I4 is preferably a radiation shield Hi. The cathode structure thus far described is preferably mounted'on an insulating disk l1 and the cathode connection is preferably made by a lead l8 extending therethrough and the return lead for the heating current may be through the enclosure l4 and radiation shield l6 to the lead I!) extending through the casing. The load circuit 20 is connected between the anode l2 and one of the cathode leads such as I8.

Adjacent the opening I is a cover or plug 2| for the opening l5. This cover or plug is adapted, when lowered, to gradually restrict and even close the opening l5 in the enclosure M. This cover member may be electrically operated by any suitable means and in my preferred embodiment I utilize a bimetal strip 22 supported on an insulating rod or standard 23.

Surrounding the bimetal strip is a heating coil 24 having leads 25 and 26 extending to a shunt relationship with a suitable inductance or resistance 21 in the load circuit 20. The connection of the coil 24 with the device 21' may be adjusted by any suitable means as by the taps 28.

The opening l5 provides the path for the electrons traveling from the cathode l3 to the anode l2. Various causes may provide such an increase in the amount of this current that would be damaging to the tube itself or to valuable apparatus in the load circuit. The heating coil 24 about the bimetal 22 is adjusted, together with the taps 28 on their resistance or inductance 21, so that an increase in current in the load circuit above a predetermined value will actuate the bimetal to curve downward and gradually restrict the discharge path for the electrons through the opening l5. When the opening I5 is saturated with electrons, a further restriction will decrease the electron current therethrough in response to a given voltage between the main electrodes. Accordingly, as the cover or plug 2| restricts the area through the opening I5, the electron current through the tube will be decreased, and likewise the current through the load circuit. Reference is made to the copending application of Erwin F. Lowry, Serial No. 97,978 filed August 26, 1936 for Current limiting apparatus, which more fully sets forth the theory connected with such a restricted opening.

The tube will accordingly automatically cut down or shut off the current through the tube in response to a current overload. If this overload is of short duration, the closure member 2| will automatically be removed when the surge has passed.

It is apparent that the construction in shape, number, and arrangement of parts can be varied. Several openings might be employed in the closure member H with a cap member to gradually restrict their openings in response to an actuating means connected in the load circuit.

Still further modifications may be made in the preferred embodiment I have disclosed. Accordingly, I desire only such limitations to be imposed on the following claims as are necessitated by the prior art.

I claim as my invention:

1. An electric discharge device comprising a container, a gaseous medium therein, an anode and an electron emitting cathode, means restricting the discharge path between said anode and container, a gaseous medium and electrodes comprising an anode and a cathode therein, and discharge restricting means including a shield having at least one opening and a closure therefor mounted between said anode and cathode, said closure being connected to a thermal responsive element.

3. An electric discharge device comprising a container, a gaseous medium and electrodes comprising an anode and a cathode therein, discharge restricting means including a shield having at least one opening and a closure therefor mounted between said anode and cathode, said closure being connected to a thermal responsive element, and heating means within said container and adjacent to said thermal responsive element having external connecting leads.

closure being connected to a bimetallic element. 15

HYMEN DIAMOND. 

